This invention relates generally to head rests and more particularly to head rests for mounting on a motor vehicle seat back and being frictionally adjustable about a horizontal axis.
Vehicle head rests which are adjustable have been provided with somewhat complex mechanisms to prevent rotation of the head rest about its support. Some examples are disclosed in U.S. Pat. Nos. 4,193,631, 4,600,240 and 4,191,423.
An object of this invention is to provide a head rest for a motor vehicle seat back having an improved simplified mounting assembly for frictional pivoting of the head rest through a limited arc of rotation about a horizontal axis.
It is another object of the present invention to provide a head rest wherein the frictional resistance to pivotal motion is variable.
A preferred embodiment of the head rest for use on a back rest of a vehicle seat according to the present invention comprises an inverted U-shaped rod having its downwardly extending legs fixed to the back rest. The transverse portion between the legs is generally horizontal and above the top of the back rest.
Wrapped over the transverse portion of the rod is an elongated friction bushing having a major and a minor axis. The bushing is elongated along the major axis and has a curved portion and a straight portion forming a J-shaped cross section along the minor axis. Alternatively, the bushing may have only a curved portion forming a C-shaped cross section along the minor axis. The curved portion of the bushing is wrapped around the transverse portion of the rod thus cupping the rod.
On the top of the rod is positioned a head rest frame which has a foam head rest pad preferably foamed in place thereon. The frame has an upright portion and a flange portion. The flange portion is attached to the rod.
A clamping bracket having a mounting flange portion and a curved, U-shaped channel clamping portion is positioned with the clamping portion over and around the curved portion of the bushing and around the rod. Along the outer edge of the mounting flange portion is a curved lip. The mounting flange portion of the bracket and the flange portion of the frame are fastened together by a bolt and nut assembly, the bolt passing through aligned holes in the flanges of the frame, the bushing, and the clamping bracket. The curved lip rests against the flange portion of the frame so that the clamping bracket is hinged against the frame along the edge of the curved lip. When tightened, the bolt and nut assembly biases the curved portion of the bracket against the bushing and in turn the bushing against the rod and the frame thus applying a frictional force to the rod resisting rotation of the frame about the rod.
The transverse portion of the rod has a pair of holes spaced apart and bored therethrough. A pair of stop pins are pressed into and through so as to project from the holes. In one preferred embodiment, the bushing and bracket each have aligned slots therethrough through which the stop pins project. When the head rest is pivoted, the pins engage against the frame to limit rotation of the head rest in one direction. The bracket engages the pins at the other end of the slots to limit rotation of the rest in the other direction. In another embodiment, the pair of pins are spaced further apart then the length of the bracket and bushing thus eliminating need for aligned slots. In this case the pins engage the frame to limit rotation of the head rest in both directions.
The degree of frictional clamping applied between the head rest and the transverse portion of the rod is variable according to the amount of torque applied to the bolt and nut assembly and according to the material chosen for the frictional bushing.
The result is a head rest which can be pivoted frictionally between a limited forward position and a backward pivoted position for the comfort and safety of the seat occupant.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when in connection with the accompanying drawing.